Why don't humans grow hair? This is the reason!

If a human and a chimpanzee stand together, the most obvious difference is probably that humans do not have the chimpanzee's shiny black hair.

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Whether it is gorillas, cats, dogs, cows or sheep, most of the mammals we come into contact with have thick hair.

Perhaps it is precisely because we don’t have it and they do that humans are so fond of these furry animals.

Of course, not all animals have impressive fur. In addition to ourselves, the hair on the bodies of whales, elephants, rhinos, hippos and other animals is very sparse or even non-existent.

Why do some animals have long hair and some are bald?

01

Why are some animals bald?

Some have abundant hair?

There are reasons why animals with less pubescent hair shed their hair, and in nature, this voluntary baldness can bring significant advantages.

For example, elephants, having shed their dense hair, can better adapt to hot temperatures without the obstruction of wet hair.

Marine mammals, such as manatees and dugongs, can also swim better in the water.

This adaptive evolution allows animals to live better and more comfortably in their environment.

The less common naked mole rats also crawl around on the ground with their flesh-pink skin every day, and the few remaining hairs on their surface look pitiful and wretched. The reason why they are bald is also quite simple - they don't need it.

Naked moles live underground all their lives. The highly cramped, oxygen-deficient environment underground is their most comfortable home.

Because the underground environment is stable, naked moles naturally do not need to face the temperature changes caused by wind and scorching sun like on the ground. For them, the most important function of hair is useless. Instead, it saves energy by not growing hair. Over time, "baldness" has become the mainstream of the population.

Of course, the underground environment is not always friendly.

At least there are a lot of small bugs underground, and naked moles, which live in social environments, can easily pass on parasites to each other, which is really a lot of trouble.

Therefore, being bald can also help them better solve the problem of parasites on their body surface and prevent them from harming the entire population.

After all, their eyesight is not very good. If they need to find insects bit by bit in the dense hair, it would be really difficult for me, a "rat"!

02

Why are we so bald?

Speaking of this, the reason why humans become bald is actually somewhat similar to that of mice - we don't need thick hair to keep warm, but we also want our skin to be more bare and easier to clean.

But the reason humans don't need hair to keep warm is that we've learned not only to use fire to keep warm, but also to make clothes.

Compared to having hair that remains the same all year round, clothes that can be changed flexibly are so convenient.

Of course, being bald can not only improve one’s ability to survive, but also improve one’s competitiveness in the marriage market.

For example, the male red bald monkeys living in South America have won the love of many females with their bald and red faces that look like big lanterns.

For red bald monkeys, baldness and redness both mean that the males have good physical fitness and are very suitable for having baby monkeys together.

However, the red bald monkey is bald and red all year round, while some other monkeys are bald intermittently.

For example, the artistically shaped gelada baboons, when in estrus, their red and swollen skin will create a peculiar pattern on their chests. From a distance, it looks like a giant red arrow that is frantically suggesting, "I'm in good health, so of course you chose me!"

This strange structure is actually called sex swelling. It is caused by local congestion and is quite common in many apes and monkeys, but its location is not as strange as on the head or chest.

For example, the mandrill has a bald butt. During the breeding season, female mandrills will climb around the trees with a butt that looks like a red apple, exuding their unique charm to the opposite sex.

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Red like a monkey's butt, this is probably the conclusion drawn from observing this phenomenon!

Of course, using baldness to show off one's physique is not just exclusive to monkeys. Birds are also eager to show off their baldness.

The red-crowned crane, which looks elegant and beautiful, actually has a real bald head. Its "red crown" is actually the bright red color of the exposed skin.

This piece of skin is not only bright red, but also covered with fleshy warts. If you look closely, it really doesn't look pretty at all.

For the red-crowned crane, the larger the bald area and the redder and brighter the body, the better. Naturally, it can be more successful in the love field and attract the female bird of its choice to dance with it.

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Here we are mentioning humans again. In fact, human naked skin has the same function.

Although human skin does not redden, bare skin better displays a healthy state, free of parasites and wounds;

In the primitive era, this was a very important asset for marriage!

Therefore, over time, the "balder" genes were passed down and became the mainstream of human beings.

Author: Sydney

Review | Huang Chengming, Researcher at the Institute of Zoology, Chinese Academy of Sciences

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